This invention relates to a special effect apparatus for a video signal and more particularly to a special effect apparatus which produces a special effect image in which image transformation is changed through a plurality of predeterminedly designated knots at which respective transformation parameters are previously designated.
A special effect apparatus of this kind is disclosed in U.S. Pat. No. 4,468,688 "Controller For System For Spatially Transforming Images", for example. In such conventional special effects apparatus, image transformation can be linearly shifted from one knot to another knot by calculating interpolated parameters between the knots. However, according to the conventional special effect apparatus, it is impossible to produce a special effect image in which a speed of image transformation on a tracing curve through knots varies in accordance with a position between the knots.